Grinding, polishing, or surfacing machine



Dec. 11, 1951 o. PASCOTTO 2,573,538

' GRINDING, POLISHING, OR SURFACING MACHINE Filed Feb. 9. 1949 2 SHEETS-SHEET 1 attorney Dec. 11, 1951 QPASCQTTQ 2,578,588

GRINDING, POLISHING, OR SURFACING MACHINE Filed Feb. 9. 1949 2 SHEETS-SI-HZET 2 ]02 28 Zlmaentor 8 pAn/rffli Patented Dec. 11, 1951 UNITED STATES PATENT OFFICE GRINDING, POLISHING, OR SURFACING MACHIN 1 Claim.

This invention relates to grinding, polishing or surfacing machines of the general type of that shown in U. S. Letters Patent to Ercole Cavicchi No. 1,571,571, granted February 2, 1926, and it has for its general object so to improve the driving connections between the motor and the grinding, polishing or surfacing head of a machine of this type as to permit more efficient operation of the machine while avoiding the rapid wear of such connections which characterizes existing machines.

Machines of the type to which the invention is directed are in quite extensive use for polishing floors or side walls made of marble, mosaic. terrazzo or other compositions requiring abrasive finishing operations and usually comprise a carriage on which is mounted the motor for driving the rotary grinding or polishing head and a tank for containing water for use in the grinding or polishing operation. The machine also usually has an arm projecting horizontally from the carriage and through which extends a shaft driven by the motor and having a bevel gear connection with a vertical shaft on the lower end of which the grinding or polishing head is mounted. usually with a universal connection to said shaft.

In machines of this type as heretofore constructed provision is made for vertical movement of the grinding head carrying shaft with respect to the horizontal arm by arranging it so that it can slide directly through the bevel gear, a spring in a socket carried by the horizontal arm tending to press said vertical shaft downwardly and thus maintain the polishing or grinding head yieldingly in contact with the surface to be polished.

To provide for lubrication of the bevel gearing a gear housing is provided about it for holding the lubricant but diiliculty has been experienced with the constructions heretofore employed because of the tendency of water and particles of material abraded from the surfaces being polished to work their way up into the gear box or housing along the sliding connections between the vertical shaft and the bevel gear which drives it. Such particles or chips of the hard materials oi' which the floors or walls are composed entering the gear chamber naturally serve to effect a rapid wearing of the intermeshing gears and also work their way into the bearings of these gears. Moreover, the entry of the water into the housing obviously deleteriously affects the lubricating properties of the grease or other lubricant used for the gearing.

An important object of the present invention is so to redesign the driving connections between the driving motor and the grinding or polishing head of a machine of this type that the gear chamber of the gear housing and the gears therein are entirely siolated from the vertically sliding grinding head shaft whereby neither water nor particles of the material abraded from the surfaces that are being polished can get into the gear housing and become mixed with the lubricant therein.

With the foregoing and other objects in view the invention contemplates the provision of a hollow shaft extending entirely through the gear chamber of the gear housing and having its ends outside said chamber and sealed therefrom by its bearings, the gear which drives said shaft being mounted upon the outside of said hollow shaft and the shaft which carries the grinding or poilshing head being slidably mounted within said hollow shaft but keyed thereto to turn therewith.

An important feature of the invention is the arrangement of the spring which tends to maintain the slidable polishing head carrying shaft in extended relation to the shaft in which it slides so that this spring turns with said shafts and thus does not have to have a bearing to permit relative movement of the shafts and spring.

Another important feature of the invention is the arrangement for effecting lubrication of those parts of the relatively sliding shafts which slide upon each other.

Other objects, important features and advantages of the invention, to which reference has not hereinabove specifically been made, will appear hereinafter when the following description and claim are considered in connection with the accompanying drawings, in which Figure 1 is a side elevation of a grinding, polishing or surfacing machine embodying the present invention;

Figure 2 is a plan view of the machine shown in Figure 1;

Figure 3 is a section on the line 3-3 of Figure 2;

Figure 4 is a secetion on the line 4-4 of Figure 3. and

Figure 5 is a section on the line l5 of Figure 3.

In the illustrative embodiment of the invention a cart frame 2 carrying an axle 4 for supporting wheels 6 has bolted thereto an electric motor 8 which serves as a part of the cart body. The casing of the motor I! has connected to it a yoke I 0 carrying a hollow horizontal arm I2 in which are bearings, preferably ball bearings such as shown at I4 in Figure 3, for a. horizontal shaft I6 connected by a universal joint I8 to the driving shaft of the electric motor 8. The yoke I0 may be connected to the casing of the motor 6 in any suitable manner as by machine screws or bolts 22 so that it may be easily removed for repair of the arm and connected parts.

At its outer end the arm I2 is provided with a flange 24, shouldered to fit within the end of the housing 26 for the bevel gearing and to be connected thereto in any suitable manner. The housing 26 has a substantially cylindrical downward extension 26 in which are mounted the ball bearings 30 for the vertical hollow shaft 32 that extends through the gear chamber in the housing 26 and thus protects said gear chamber from the entry thereinto of the particles abraded from the surfaces being treated and of the water used in the polishing operations which tend to travel up along the grinding head shaft, hereinafter to be described.

As herein shown the downward extension 20 of the housing 26 is of sufficient extent to receive also the hub 34 of the bevel gear 36 that drives the vertical shaft 32. The cooperating bevel gear 36 has a hub 40 received upon and connected to the end of the shaft I6 which projects from the hollow arm I2 into the housing 26. The upper end of the shaft 32 is preferably somewhat reduced in diameter and is mounted in ball bearings 42 carried in a chambered head 44 extending upwardly from the removable cover 46 of the housing 26.

As hereinabove suggested, the shaft 32 is hollowed out inside, below its reduced upper end, to :1

provide a cylindrical chamber 48 in which is slidably mounted the shaft 50 that carries the grinding, polishing or surfacing head 52 to which the abrasive blocks 54, which engage the surface to be treated and do the polishing, are connected.

The connection between the head 52 and the shaft 50 is preferably of a substantially universal joint type and may be similar to that shown in the Letters Patent 1,571,571 hereinabove identifled, the shaft being provided with a ball end 56 received in a covered socket 58 in the head 52 and having lugs 60 projecting through slots 62 in the side walls of the socket.

As herein shown, the cylindrical chamber 46 in the shaft 32 extends full diameter substantially throughout the main part of the shaft and communicates at the reduced upper end of the shaft with a concentric extension of smaller diameter. The vertically slidable shaft 50 also has a hollow interior 66, preferably of the same diameter as the hollow interior in the reduced end of the shaft 32. The tubular passageway thus provided receives a tube or conduit 68 for the water or other lubricant supplied to the operating faces of the polishing blocks 54, this tube or conduit 68 extending down through the shaft 50 to a point sufficiently distant from the lower end of the shaft 50 to permit the relative longitudinal movement of shafts 50 and 32 provided for, as hereinafter set forth. The ball end 56 of shaft 50 is provided with an enlarged outlet I0 that in turn communicates, in all positions of relative adjustment of the ball 56 and head 52, with an opening 12 through the head 52.

As herein shown, the tube or conduit 68 is tapped into a block I4 in the upper part of the chamber 16 in the head 44, where it communicates with an L-shaped passage I8 in said block that in turn communicates with a nipple 80 tapped into an opening through the sidewall of the head 44. The nipple is adapted to receive one end of a hose 82 connected at its other end to a tank 90, mounted upon the motor 8 or otherwise suitably supported upon the motor carrying cart, in which the water or other wetting agent to be supplied to the polishing head may be stored. Any suitable hand-operated valve 92 may be provided for controlling the flow of the water from the tank 90.

To provide for limited sliding movement of the shaft 50 within the hollow shaft 32 and at the same time to insure turning of the shaft 50 with the shaft 32, these shafts may be keyed together in any suitable manner. As shown in Figures 3 and 4, a threaded pin 94, having its inner end shaped to fit in a keyway 96 in the shaft 50, may be screwed into a threaded opening through the side wall of the shaft 32, the keyway 96 being of limited length, as shown in Figure 3. A spring 98, seated in the upper end of the main cylindrical chamber 46 and bearing upon the shouldered upper end I00 of the shaft 50, holds said shaft 50 normally in its extended relation to the shaft 32.

To insure driving of the shaft 32 by means of the bevel gear 36 the hub 34 of the bevel gear 36 is preferably connected to the shaft 32 as shown in section in Figure 5 of the drawings. As shown in Figure 5, a key I02 having an enlarged head I04 adapted to be received in a keyway I06, extending throughout the length of the hub 34 of the gear 36, extends through the side wall of the shaft 32 and its inner key edge is received in a keyway I08 in the shaft 50. In assembling these parts it will be seen that the key I02 is placed into the position shown in Figure 5 and that then the hub 34 of the gear 36 is slipped over the shaft 32, the head I04 of the key I02 being first brought into register with the keyway I06 in the hub 34. Preferably the shaft 32 is provided with a shoulder IIIl against which the upper end of the gear 36 bears when the gear is in assembled relation to the shaft 32.

When the parts have been assembled as shown in Figure 3 of the drawings, it is advantageous, in order to prevent entry of water and abraded particles into the bearings of the shaft 32, to provide a stufling box in the lower end of the extension 26 of the housing 26. As shown at Il2, the lower end of the shaft 32 is threaded to receive a threaded collar II4 which confines the inner raceways of the ball bearings 30 upon the shaft 32 and at the same time holds the bevel gear 36 against the shoulder IIO on the shaft 32. The lower end of the extension 28 of the housing 26 is internally threaded to receive a gland II6 of a stufiing box and this gland serves so to confine packing H8 between the outer face of the collar II4 on the shaft 32 and the inner face of the gland II6 as to provide a substantially watertight closure of this end of the extension 26 of the housing 26. Spanner sockets I20 are preferably provided in the lower face of the gland II6 to facilitate adjustment and removal thereof.

To permit lubrication of the relatively movable engaging surfaces of the shafts 50 and 32, an oil opening I22, through the wall of the shaft 32 into the chamber 48 within said wall, may be provided in that part of the shaft that lies within the gear chamber in the housing 26, this opening preferably entering the chamber 48 at a point slightly above the upper end of the shaft 50 when in its extended relation to the shaft 32. To prevent any water and any particles contained therein, which might have entered the chamber 48, from passing through this oil opening into the gear chamber, a check valve is preferably provided in the enlarged outer part E24 of the opening I22, this check valve comprising a ball I26 pressed by a spring I against a valve seat on a centrally drilled screw I30 tapped into the enlarged end I24 of the oil opening. With this arrangement it will be seen that any suction movement of the shaft within the shaft 32, that is an outward movement thereof under the action of the spring 93, will draw oil into the chamber 48 through the check valve l'dfi and that any compression movement of the shaft 50, as when it is forced inwardly against the spring 88, will seat the valve I559 more tightly and prevent ingress into the gear chamber in the lions ing 26 of any of the contents of the chamber 8.

As hereinabove pointed out, the tube or conduit 68 does not turn with the shaft 50 but extends concentrically through he hollow interior 6B of said shaft to a point sufficiently distant from the lower end of the shaft 50 to permit movement of said shaft 50 up and down in the shaft 32. The water for lubricating the operations of the grinding or surfacing head is, therefore, discharged into the hollow interior 66 of the lower part of the shaft 59 and travels down through this hollow interior from the discharge end of the tube or conduit 68 to the outlet 10. To prevent this water, and any particles which it contains, from flowing freely back up the hollow interior of the shaft 59 on the outside of the tube 68, in the substantial clearance that must be provided to permit free relative turning of the shaft 50 about the tube 68, any suitable packing such as that shown at I32 may be fitted upon the outside or the lower end of the tube 68 to seal the clearance between the wall of the hollow interior 66 of the shaft 50 and the lower end of the tube 68, thus preventing flow of water up the shaft 59 between the tube 68 and the wall of the hollow interior 66.

To provide for cleaning out the tube 68, an opening I34, normally closed by screw plug I36, is provided in the upper end of the head 44, this opening communicating with that part of the chamber 16 in the head 44 which is above the block I I and also communicating with an opening I38 in the upper part of the block M which is in line with the tube 68. By removing the plug I36 a cleanout wire can be run down through the tube 68, through the lower end of the hollow interior 66 of the shaft 50 and through the outlet 10 in said shaft to clean out the tube. The wire may also, as shown, be run down through the head 52 is in position on the shaft 50 when the cleaning out is being effected.

To prevent material from the chamber 48 in the shaft 32 from working up along the tube 68 into the space between the ball bearings 42 and the block I4, a stuffing box 64 is preferably provided in the upper end of the reduced extension of the shaft 32 that lies within the ball bearings 42.

From the foregoing description it will be seen that the present invention provides substantially water and dirt proof driving connections between the motor 8 and the polishing head 52 of a machine of the class described. By keeping particles abraded from the surfaces being treated ill! from entering into the mechanism and by also excluding water from the interior of the driving connections, wear of these connections has been greatly reduced and particularly wear of the bearings. By thus eliminating excessive wear it has become possible to drive the polishing head 52 consistently at a higher speed than was possible with machines of this type as heretofore constructed, thereby materially increasing the efficiency of the machine as a Whole.

It will further be seen that by eliminating wear such as would cause the bearings to become loose, the effort required of an operator of the mach ne is greatly reduced. In fact, as compared with old machines now in use, a polishing machine constructed as herein described can not only be operated at much higher speed, but the elimination of vibration due to wear insures a more uniform polishi g effect and very much less strain on the operator.

What is claimed as new is:

A machine of the class described having. in combination, a gear housing provided with opposed spaced bearings, a hollow driven shaft rotatably mounted in said bearings and having its ends extending beyond the housing, a driving shaft projecting into said housing at substantially right angles to said driven shaft, gearing operatively connecting said shafts, said gearing including a bevelled gear fixed upon said hollow driven shaft, the hollow interior of said driven shaft being completely sealed off from the interior of said housing, a hollow tool carrying shaft axially slidable within said driven shaft and extending outwardly and downwardly therefrom. means rotatably connecting said tool carrying shaft to said driven shaft, said tool carrying shaft extending axially into the driven shaft and spaced from one end thereof to form a chamber, a coil spring confined between the wall of the chamber and the inner end of the tool carrying shaft for normally urging the latter outwardly relative to the housing, said spring being rotatable with said driven shaft, and a fixed liquid conduit extending coaxially through said hollow driven shaft and said hollow tool carrying shaft to a discharge point spaced from the tool carrying shaft a distance sufficient to permit the unobstructed axial movement thereof into said driven shaft, the parts being constructed and arranged to permit axial displacement of the tool carrying shaft relative to the driven shaft so as to completely protect the rotary and sliding bearings within the housing opening 12 in the head 52 in the event that the 1 from ingress of water and abrasive material.

DANTE PASCOTTO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,308,933 Cavicchi July 8, 1919 1,550,102 Schlueter Aug. 18, 1925 1,571,571 Cavicchi Feb. 2, 1926 2,097,730 Mall Nov. 2, 1937 2,106,035 Mall Jan. 18, 1939 2,316,886 Pasucchl Apr. 20, 1943 

